Modern human origins in Australasia: Testing the predictions of competing models

Brief communication: Artificial cranial modification in Kow Swamp and Cohuna

The crania from Kow Swamp and Cohuna have been important for a number of debates in Australian paleoanthropology. These crania typically have long, flat foreheads that many workers have cited as evidence of genetic continuity with archaic Indonesian populations, particularly the Ngandong sample. Other scientists have alleged that at least some of the crania from Kow Swamp and the Cohuna skull have been altered through artificial modification, and that the flat foreheads possessed by these individuals are not phylogenetically informative. In this study, several Kow Swamp crania and Cohuna are compared to known modified and unmodified comparative samples. Canonical variates analyses and Mahalanobis distances are generated, and random expectation statistics are used to calculate statistical significance for these tests. The results of this study agree with prior work indicating that a portion of this sample shows evidence for artificial modification of the cranial vault. Many Kow Swamp crania and Cohuna display shape similarities with a population of known modified individuals from New Britain. Kow Swamp 1, 5, and Cohuna show the strongest evidence for modification, but other individuals from this sample also show evidence of culturally manipulated changes in cranial shape. This project provides added support for the argument that at least some Pleistocene Australian groups were practicing artificial cranial modification, and suggests that caution should be used when including these individuals in phylogenetic studies.

The Watinglo mandible: a second terminal Pleistocene Homo sapiens fossil from tropical Sahul with a test on existing models for the human settlement of the region

This paper analyses a fossil human mandible, dated to circa 10ka, from Watinglo rockshelter on the north coast of Papua New Guinea. The fossil is metrically and morphologically similar to male mandibles of recent Melanesians and Australian Aborigines. It is distinguished from Kow Swamp and Coobool Creek male mandibles (Murray Valley, terminal Pleistocene) by being smaller and having different shape characteristics, as well as smaller teeth and a slower rate of tooth wear. It pairs with the Liang Lemdubu female (Late Glacial Maximum, Aru Islands) in suggesting that the morphology of the terminal Pleistocene inhabitants of tropical Sahul was gracile compared to their contemporaries within the southern Murray drainage. An explanatory scenario for this morphological contrast is developed in the context of the Homo sapiens early fossil record, Australasian mtDNA evidence, terminal Pleistocene climatic variation, and the possibility of multiple entry points into Sahul.

A 150-year conundrum: cranial robusticity and its bearing on the origin of aboriginal australians

The origin of Aboriginal Australians has been a central question of palaeoanthropology since its inception during the 19th Century. Moreover, the idea that Australians could trace their ancestry to a non-modern Pleistocene population such as Homo erectus in Southeast Asia have existed for more than 100 years, being explicitly linked to cranial robusticity. It is argued here that in order to resolve this issue a new program of research should be embraced, one aiming to test the full range of alternative explanations for robust morphology. Recent developments in the morphological sciences, especially relating to the ontogeny of the cranium indicate that character atomisation, an approach underpinning phylogenetic reconstruction, is fraught with difficulties. This leads to the conclusion that phylogenetic-based explanations for robusticity should be reconsidered and a more parsimonious approach to explaining Aboriginal Australian origins taken. One that takes proper account of the complex processes involved in the growth of the human cranium rather than just assuming natural selection to explain every subtle variation seen in past populations. In doing so, the null hypothesis that robusticity might result from phenotypic plasticity alone cannot be rejected, a position at odds with both reticulate and deep-time continuity models of Australian origins.

Artificial cranial deformation in Kow Swamp 1 and 5: a response to Curnoe (2007)

Recently, Curnoe (2007) tested the predictions of competing models of modern human origins using three crania from Australia: Kow Swamp 1 and 5 and Keilor. The Kow Swamp specimens have long been suspected of having been altered through artificial deformation of the skull. Though Curnoe (2007) provided assurances that no evidence of deformation is present in those specimens, the current study retests the hypothesis that these Australian specimens are artificially deformed. The Australian crania are compared to known deformed individuals from New Britian through canonical variates analysis, and the resulting Mahalanobis distances are examined for statistical significance with random expectation statistics. The results show that Kow Swamp 1 and 5 have strong shape similarities to known deformed individuals, and both crania are very different in shape from Keilor. Keilor is statistically significantly different in shape from both Kow Swamp specimens and all of the known deformed specimens. These findings cast doubt on Curnoe's (2007) conclusions of a shared Australian cranial morphology as well as the retention of an archaic suite of morphologies in the Australians.